In typical usage, various types of electronic devices such as computers, cell phones, remote controls, PDAs, radios, and other electronic articles require human contact and are thus exposed to possible liquid spills and encroachment by rain, and/or water laden vapor including high humidity and fogs, etc. The cost of replacing electronic circuitry due to liquid compromise, which typically leads to shorts in the system, failure of keyboard elements and to sticky keys on keyboards and keypads, is great when considering that computer keyboards are so prevalent, and their use in daily activities, such as in cell phones and laptop computers, is so commonplace. Thus, there has been great interest in a means of protecting such electronic devices from liquid spills and the resulting sticky keys on keyboards and keypads. What is meant by keypads is any type of key button or pad which is mechanically actuated on an electronic device. The sticky key problem is mechanical: once two contact surfaces come together, they stick to each other.
Most attempts to block liquid spills in electronic devices involve the use of an impermeable liquid barrier that diverts the flow of liquids that should fall into the crevices of a keypad or keyboard. The impermeable barriers in the prior art, such as disclosed in U.S. Pat. No. 5,681,122 involve the use of a tray having walls and a spillway that is located below the external facie of the computer keyboard but above the electronic equipment, the tray having formations to allow the keys of the keyboard to float through. Spills would then fall into the spaces between the facie and keys and into the tray to be collected at the spillway. Other means of protecting electronic devices from liquid spills include such means as disclosed in U.S. Pat. No. 5,491,478, wherein a unitary molded seal membrane is sealed over the top of keys on a cell phone or keyboard keypad, thus directly blocking the flow of spills. A third protection system is a thermal heat seal of a laminated PVC membrane with the electronic traces contained within the seal. This, however, offers only limited water resistance, and breaks down over time.
There are numerous problems with the prior art protection systems. The use of such means as a tray requires that the liquid fall downwardly directly into the keypad or keyboard. This does not take into account the encroachment of moisture due to rain, fog, or spills that are substantially non-vertical. The problem with the membrane-type of barrier is that such barriers prevent free and unhindered use of the keyboard or keypad. Further, these membranes typically wear over time and become translucent or even opaque, thus requiring replacement. Since these articles must be fastened securely around the keypad or keyboard, it is not convenient for a typical user to easily replace them. As mentioned above, sealed plastic laminates offer only minimal protection and require thin silver traces, which is subject to corrosion, fatigue and cracking.
There is thus a need for an improved method of protecting the electronic circuitry and keypads and keyboards in devices such as cell phones, ATM machine keypads, laptop computer keypads, remote controls, PDAs, radios, and other devices where the threat of liquid spill or moisture exposure may be present. This need is heightened by the fact that electronic equipment such as laptop computers, cell phones, phones in phone booths, marine electronic equipment, and other electronic equipment finds more widespread outdoor use.
Accordingly, what is needed is a system and method for protecting electronic circuitry and preventing sticky keys on keyboards or keypad devices due to spills. The present invention addresses such a need.